我在 centos5.6 上使用 exim 的自定义版本（与 afterlogic pro mailsuite 捆绑在一起）。系统无法发送到 yahoo 或 gmail 等远程邮件服务器，并出现此错误：
[email protected] R=dnslookup defer (-1): host lookup did not complete
我可以使用 dig 命令查找 gmail.com dns 记录：
#dig mx gmail.com
; <<>> DiG 9.3.6-P1-RedHat-9.3.6-16.P1.el5 <<>> mx gmail.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2234
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;gmail.com. IN MX
;; ANSWER SECTION:
gmail.com. 3600 IN MX 30 alt3.gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 20 alt2.gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 5 gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 10 alt1.gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 40 alt4.gmail-smtp-in.l.google.com.
;; Query time: 16 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Mar 16 16:23:27 2012
;; MSG SIZE rcvd: 150
我使用 exim 运行了调试命令，结果如下：
#bin/exim -bt -d-resolver [email protected]
Exim version 4.76 uid=0 gid=0 pid=2368 D=fbb95cfd
Berkeley DB: Berkeley DB 5.2.36: (September 14, 2011)
Support for: crypteq iconv() OpenSSL Content_Scanning DKIM
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch dbm dbmnz mysql
Authenticators: cram_md5 plaintext spa
Routers: accept dnslookup ipliteral manualroute queryprogram redirect
Transports: appendfile/maildir autoreply pipe smtp
Fixed never_users: 0
Size of off_t: 8
Compiler: GCC [4.1.2 20080704 (Red Hat 4.1.2-51)]
Library version: OpenSSL: Compile: OpenSSL 1.0.0e 6 Sep 2011
Runtime: OpenSSL 1.0.0e 6 Sep 2011
Library version: PCRE: Compile: 8.13
Runtime: 8.13 2011-08-16
Total 7 lookups
Library version: MySQL: Compile: 5.1.56 [Source distribution]
Runtime: 5.1.56
WHITELIST_D_MACROS unset
TRUSTED_CONFIG_LIST unset
changed uid/gid: forcing real = effective
uid=0 gid=0 pid=2368
auxiliary group list: <none>
seeking password data for user "exim": cache not available
getpwnam() succeeded uid=3000 gid=3000
seeking password data for user "root": cache not available
getpwnam() succeeded uid=0 gid=0
configuration file is /usr/mailsuite/etc/exim
log selectors = 0000cefe 00233821
trusted user
admin user
seeking password data for user "exim": cache not available
getpwnam() succeeded uid=3000 gid=3000
seeking password data for user "exim": using cached result
getpwnam() succeeded uid=3000 gid=3000
seeking password data for user "exim": using cached result
getpwnam() succeeded uid=3000 gid=3000
originator: uid=0 gid=0 login=root name=root
sender address = [email protected]
Address testing: uid=0 gid=3000 euid=0 egid=3000
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Testing [email protected]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Considering [email protected]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
routing [email protected]
--------> dnslookup router <--------
local_part=someuser domain=gmail.com
checking domains
search_open: mysql "NULL"
search_find: file="NULL"
key="SELECT name FROM awm_domains WHERE name = 'gmail.com' AND is_internal = 1 " partial=-1 affix=NULL starflags=0
LRU list:
internal_search_find: file="NULL"
type=mysql key="SELECT name FROM awm_domains WHERE name = 'gmail.com' AND is_internal = 1 "
database lookup required for SELECT name FROM awm_domains WHERE name = 'gmail.com' AND is_internal = 1
MySQL query: SELECT name FROM awm_domains WHERE name = 'gmail.com' AND is_internal = 1
MYSQL new connection: host=localhost port=0 socket=/usr/mailsuite/tmp/mysql.sock database=exim user=root
MYSQL: no data found
lookup failed
gmail.com in ""? no (end of list)
gmail.com in "! +local_domains"? yes (end of list)
calling dnslookup router
dnslookup router called for [email protected]
domain = gmail.com
DNS lookup of gmail.com (MX) succeeded
DNS lookup of gmail-smtp-in.l.google.com (A) succeeded
DNS lookup of alt1.gmail-smtp-in.l.google.com (A) succeeded
DNS lookup of alt2.gmail-smtp-in.l.google.com (A) succeeded
DNS lookup of alt3.gmail-smtp-in.l.google.com (A) succeeded
DNS lookup of alt4.gmail-smtp-in.l.google.com (A) succeeded
fully qualified name = gmail.com
host_find_bydns yield = HOST_FOUND (2); returned hosts:
gmail-smtp-in.l.google.com 209.85.225.27 MX=5
alt1.gmail-smtp-in.l.google.com 173.194.76.27 MX=10
alt2.gmail-smtp-in.l.google.com 74.125.115.27 MX=20
alt3.gmail-smtp-in.l.google.com 173.194.67.26 MX=30
alt4.gmail-smtp-in.l.google.com 173.194.65.26 MX=40
set transport remote_smtp
queued for remote_smtp transport: local_part = someuser
domain = gmail.com
errors_to=NULL
domain_data=NULL localpart_data=NULL
routed by dnslookup router
envelope to: [email protected]
transport: remote_smtp
host gmail-smtp-in.l.google.com [209.85.225.27] MX=5
host alt1.gmail-smtp-in.l.google.com [173.194.76.27] MX=10
host alt2.gmail-smtp-in.l.google.com [74.125.115.27] MX=20
host alt3.gmail-smtp-in.l.google.com [173.194.67.26] MX=30
host alt4.gmail-smtp-in.l.google.com [173.194.65.26] MX=40
[email protected]
router = dnslookup, transport = remote_smtp
host gmail-smtp-in.l.google.com [209.85.225.27] MX=5
host alt1.gmail-smtp-in.l.google.com [173.194.76.27] MX=10
host alt2.gmail-smtp-in.l.google.com [74.125.115.27] MX=20
host alt3.gmail-smtp-in.l.google.com [173.194.67.26] MX=30
host alt4.gmail-smtp-in.l.google.com [173.194.65.26] MX=40
search_tidyup called
close MYSQL connection: localhost:(/usr/mailsuite/tmp/mysql.sock)/exim/root
我真的很茫然，如果能提供任何帮助我都会感激不尽。
答案1
事实证明，MTA 无法通过外部 DNS 解析器解析 DNS 记录。我在本地服务器中安装了 dnsmasq，并将其作为 /etc/resolv.conf 中的第一个条目，exim 和 postfix 都能够发送到远程服务器。
答案2
Exim 不会以 的身份运行root。它使用的默认非 root 用户 ID 是作为构建的一部分进行硬编码的。在您的情况下，它似乎是exim。添加一个exim具有组的用户 ID exim，它应该可以运行。
编辑：日志上的滚动条不见了。Exim 似乎选择了正确的路由器，DNS 查找成功。但是，没有迹象表明正在与远程服务器建立连接。尝试使用 telnet 连接到一个或多个 IP，看看是否可以连接到 SMTP 端口。命令
telnet 209.85.225.27 25
应产生如下结果：
Trying 209.85.225.27...
Connected to 209.85.225.27.
Escape character is '^]'.
220 mx.google.com ESMTP el4si7116293icb.3
以 220 开头的行表示您已连接到服务器。如果成功，请键入QUIT以关闭连接。如果没有成功，则可能是防火墙阻止了传出的 SMTP 连接。